The famous outlaw Rob Roy MacGregor grew up on the shores of Loch Katrine in the late 17th century. 'Katrine' derives from the Gaelic 'cateran', a Highland robber. Rob Roy once imprisoned the Duke of Montrose’s factor (his agent and rent collector) on the steep sided island Eilean Dharag, since known as Factor’s Island.

The Loch has been the water supply for the city of Glasgow and its suburbs since 1859. The water level rose at this time, so a stone wall was built to protect Factor’s Isle. The surrounding land is free from development and agriculture and is much as it was in Rob Roy’s time.